Grok 4.5 Enters Private Beta at SpaceX and Tesla
Elon Musk announced on June 28, 2026 that Grok 4.5 has entered private beta testing at SpaceX and Tesla, marking the first real-world deployment of xAI's latest and most powerful model yet.
The Model
Grok 4.5 is built on xAI's 1.5 trillion parameter V9 foundation model — approximately three times larger than the 500 billion parameter v8-small that currently handles production Grok traffic on X. It represents a 50% scale increase from Grok 4.4 (approximately 1 trillion parameters) in just over one month.
A distinctive feature is the inclusion of Cursor training data. SpaceX acquired Anysphere (Cursor's parent company) for $60 billion in June 2026, and Cursor IDE session data has been used in supplemental training to sharpen coding and technical reasoning performance.
Performance Claims
Musk characterized internal evaluations as showing performance 'close to, perhaps exceeding Opus.' Developer Mehul Mohan, who tested an early build, described the experience as 'similar to Opus.' No independent third-party benchmarks have been published as of July 4.
Deployment Strategy
xAI is using SpaceX and Tesla as production evaluation environments before broader release. SpaceX's aerospace engineering workflows and Tesla's vehicle software development provide real-world technical tasks that Musk argues are harder than any benchmark.
The Road Ahead
Musk confirmed that SpaceX plans to release 'completely new models trained from scratch' every month through the end of 2026 — a development cycle faster than any other frontier lab has publicly committed to. On the longer horizon, Grok 5 is targeting 6 to 10 trillion parameters and is training on Colossus 2 alongside six other concurrent training runs.
